Helium Recovery From Natural Gas Integrated With NGL Recovery

ABSTRACT

The invention relates to a process for producing a helium-enriched vapor stream, a methane-enriched vapor stream, and a liquid stream enriched in hydrocarbons heavier than methane from a pressurized, multicomponent, multiphase stream comprising methane (C 1 ), helium (He) and hydrocarbons heavier than methane (C 2+ ). The process includes cooling the multiphase stream to produce at least one vapor stream enriched in helium and at least one liquid stream, withdrawing at least a portion of the at least one vapor stream as a helium-enriched product stream, passing at least a portion of the at least one liquid stream to a demethanizer, withdrawing from the demethanizer a vapor enriched in methane (C 1 ), and withdrawing from the demethanizer a liquid enriched in hydrocarbons heavier than methane (C 2+ ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/103,436, filed 7 Oct. 2008.

FIELD OF THE INVENTION

The present invention relates to an improved process for cryogenicseparation of natural gas. More particularly, the present inventionrelates to an improved process for cryogenically removing helium andnatural gas liquids (NGLs) from natural gas to produce a product streamenriched in helium, a liquid product stream enriched in NGLs, and agaseous product stream enriched in methane.

BACKGROUND

This section is intended to introduce various aspects of the art, whichmay be associated with exemplary embodiments of the present invention.This discussion is believed to assist in providing a framework tofacilitate a better understanding of particular aspects of the presentinvention. Accordingly, it should be understood that this section shouldbe read in this light, and not necessarily as admissions of prior art.

Because of its clean burning qualities and convenience, natural gas hasbecome widely used in recent years. The composition of natural gas canvary significantly. As used in this disclosure, a natural gas streamcontains methane (C₁ as a major component. The natural gas willtypically contain contaminants such as water, carbon dioxide, hydrogensulfide, dirt, and iron sulfide; hydrocarbons such as ethane (C₂),propane (C₃), and higher hydrocarbons; and diluent gases such asnitrogen and helium.

In order to produce natural gas of a purity suitable for commercial use,a natural gas stream from a gas-bearing reservoir may have to beseparated to enrich the methane content of the gas stream.

Natural gas is often treated to remove impurities such as carbondioxide, water, and non-hydrocarbon acid gases. Natural gas is oftenfurther processed to separate and recover natural gas liquids (NGLs),which may include hydrocarbons such as ethane, propane, butanes,pentanes, and sometimes higher molecular weight components. NGLs arevaluable as raw materials for preparing various petrochemicals. NGL issometimes referred to as C₂₊.

Various distillation methods have been considered for recovering NGLcomponents from natural gas. The NGL is typically separated from methaneand more volatile components such as nitrogen and helium in one or moredistillation towers. The towers are often referred to as demethanizer ordeethanizer columns. Processes employing a demethanizer column separatemethane and other volatile components from ethane and heaviercomponents. The methane fraction is typically recovered as purified gas(containing small amounts of inerts such as nitrogen, CO₂, etc.) forpipeline delivery. NGLs are recovered as much as practical from the feedgas.

One NGL recovery process is known as the Gas Subcooled Process (“GSP”),which is disclosed in U.S. Pat. Nos. 4,140,504; 4,157,904; and4,278,457. In the GSP process, a portion of a natural gas feed stream iscondensed and subcooled, flashed down to the demethanizer operatingpressure, and supplied to the demethanizer as its top feed for reflux.The remainder of the feed gas is also expanded to lower pressure(typically using a turboexpander for vapor streams) and fed to thedemethanizer at one or more intermediate feed points. Another process,known as the Recycle Split-vapor Process (“RSV”), which is disclosed inU.S. Pat. No. 5,568,737, is a residue gas recycle process in which theoverhead gas (residue gas) of a demethanizer (or a deethanizer) iscompressed and cooled, and is depressurized to make a low-temperatureliquid, and then the liquid is supplied as a reflux to the demethanizer(or the deethanizer).

Helium is another component of natural gas in certain natural gasfields, typically present in small concentrations. The presents ofhelium in the natural gas reduces the heating value of the natural gas.Also, helium may have independent commercial uses if it can beeconomically separated from the natural gas. Consequently, theseparation of helium from natural gas may have a twofold economicbenefit, namely, enhancement of the natural gas heating value andproduction of a marketable gas such as helium.

Numerous processes are known in the art for the cryogenic separation ofhelium from a natural gas stream. Among these cryogenic processes arethe multi-stage flash cycle process and the high pressure distillationprocess. The cryogenic processes typically subject the helium-bearingnatural gas to successively lower temperatures to condense and therebyremove from the natural gas those components therein having boilingpoints higher than that of helium. These components generally include,in descending order of their boiling points, hydrocarbons heavier thanmethane, methane itself, and nitrogen.

In the flash cycle, which is disclosed for example in U.S. Pat. No.3,260,058, feed gas is partially liquefied and phase separated.Dissolved helium in the liquid portion is recovered by severalsubsequent flash steps in which small amounts of helium-rich vapor areflashed off and eventually added to the bulk helium-rich stream.

In the distillation (high pressure stripping) process, feed gas is atleast partially liquefied and fed to a distillation step in whichdissolved helium is stripped from the liquid at feed pressure. The highpressure distillation process has the advantage of higher helium contentin the helium-enriched stream than the flash cycle. In addition, sincethe helium-enriched stream is produced at feed pressure, the productstreams from the subsequent processing steps can be returned at higherpressure, thereby reducing energy consumption for the crude heliumstream recompression.

Processes have been proposed for integrating the recovery of helium withNGL recovery. See, for example, SPE paper number 24292, entitled“Process Requirements and Enhanced Economics of Helium Recovery FromNatural Gas”, presented at the SPE Mid-Continent Gas Symposium inAmarillo, Tex., Apr. 13-14, 1992, which discloses operating a NGLsection of a process with a nitrogen recovery unit (“NRU”) and a heliumrecovery unit (“HRU”). In such processes, a natural gas stream is feedto a distillation column that produces a NGL stream and one or morevapor streams that are passed to an integrated NRU/HRU unit. The NRU/HRUunit produces a vapor stream enriched in helium, a vapor stream enrichedin nitrogen, and a residual gas stream enriched in methane.

The prior art has long sought methods for improving efficiency andeconomics of processes for separating and recovering helium and naturalgas liquids from natural gas. Accordingly, there has been a need formore efficient and more economical methods for performing thisseparation.

SUMMARY

In general, in one aspect, the invention relates to a process ofproducing a helium-enriched vapor stream, a methane-enriched vaporstream, and a liquid stream enriched in hydrocarbons and other compoundsheavier than methane from a pressurized, multicomponent, multiphasestream comprising methane (C₁), helium (He) and hydrocarbons heavierthan methane (C₂₊). The process comprises cooling the gas stream toproduce at least one vapor stream enriched in helium and at least oneliquid stream, withdrawing at least a portion of the at least one vaporstream as a helium-enriched product stream, passing at least a portionof the at least one liquid stream to a demethanizer, withdrawing fromthe demethanizer a vapor enriched in methane (C₁), and withdrawing fromthe demethanizer a liquid enriched in hydrocarbons heavier than methane(C₂₊).

In another aspect, the invention relates to a process comprising passinga natural gas feed stream containing helium and NGLs into a first phaseseparator to produce a first vapor phase and a first liquid phase,withdrawing the first vapor phase from the first phase separator,separating the first vapor phase into a second vapor phase and a thirdvapor phase, cooling the second vapor phase by indirect heat exchange ina heat exchanger, expanding the cooled second vapor phase to produce areduced-pressure vapor phase and reduced-pressure liquid phase, andpassing the reduced-pressure vapor and liquid phases to a second phaseseparator, withdrawing from the second phase separator a helium-enrichedvapor phase, withdrawing liquid from the second phase separator andpassing the withdrawn liquid to a first flow regulating device, passingliquid from the first flow regulating device to a demethanizer,expanding the third vapor phase to produce a reduced-pressure vaporphase and reduced-pressure pressure liquid phase, and passing thereduced-pressure vapor and liquid phases to the demethanizer,withdrawing liquid from the first phase separator and passing thewithdrawn liquid to a second flow regulating device, passing liquid fromthe second flow regulating device to the demethanizer, withdrawing fromthe demethanizer a vapor enriched in methane (C₁), and withdrawing fromthe demethanizer a liquid enriched in hydrocarbons heavier than methane(C₂₊).

Other aspects and advantages of the invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent from the following detailed description taken in combinationwith the appended drawings, in which:

FIG. 1 is a schematic diagram of one embodiment of the present inventionfor producing products from natural gas in which helium recovery isintegrated into a GSP process for NGL recovery.

FIG. 2 is a schematic diagram of another embodiment of the presentinvention for producing products from natural gas in which heliumrecovery is integrated into a GSP process for NGL recovery.

FIG. 3 is a schematic diagram of another embodiment of the presentinvention for producing products from natural gas in which heliumrecovery is integrated into a RSV process for NGL recovery.

FIG. 4 is a schematic diagram of another embodiment of the presentinvention for producing products from natural gas in which heliumrecovery is integrated into a GSP process for NGL recovery.

FIG. 5 is a schematic diagram of another embodiment of the presentinvention for producing products from natural gas in which heliumrecovery is integrated into a RSV process for NGL recovery.

FIG. 6 is a schematic diagram of another embodiment of the presentinvention for producing products from natural gas in which heliumrecovery is integrated into a RSV process for NGL recovery.

FIG. 7 is a schematic diagram of another aspect of the invention whichillustrates cooling by refrigeration instead of expansion devices.

While the present disclosure is susceptible to various modifications andalternative forms, specific example embodiments thereof have been shownin the drawings and are herein described in detail. It should beunderstood, however, that the description herein of specific exampleembodiments is not intended to limit the disclosure to the particularforms disclosed herein, but on the contrary, this disclosure is to coverall modifications and equivalents as defined by the appended claims. Itshould also be understood that the drawings are not necessarily toscale, emphasis instead being placed upon clearly illustratingprinciples of exemplary embodiments of the present invention. Moreover,certain dimensions may be exaggerated to help visually convey suchprinciples. For purposes of clarity, not every component is labeled inevery figure, nor is every component of each embodiment of the inventionshown where illustration is not necessary to allow those of ordinaryskill in the art to understand the invention. In the drawings, the samereference numerals designate like or corresponding, but not necessarilyidentical, elements throughout the figures. Various required subsystemssuch as, but not limited to, valves, pumps, motors, reboilers, flowstream mixers, control systems, and sensors have been deleted from thedrawings for the purposes of simplicity and clarity of presentation.Such subsystems would be provided in accordance with standardengineering practice.

DETAILED DESCRIPTION

In the following detailed description section, the specific embodimentsof the present invention are described in connection with preferredembodiments. However, to the extent that the following description isspecific to a particular embodiment or a particular use of the presentinvention, this is intended to be for exemplary purposes only and simplyprovides a description of the exemplary embodiments. Accordingly, theinvention is not limited to the specific embodiments described below,but rather, it includes all alternatives, modifications, and equivalentsfalling within the true spirit and scope of the appended claims.

In the interest of clarity, not all features of an actual implementationare described in this disclosure. It will of course be appreciated bypersons skilled in the art that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated bypersons skilled in the art that such a development effort might becomplex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthe present disclosure.

DEFINITIONS

Various terms as used herein are defined below. To the extent a termused in a claim is not defined below, it should be given the broadestdefinition persons in the pertinent art have given that term asreflected in at least one printed publication or issued patent.

As used herein, “a” or “an” entity refers to one or more of that entity.As such, the terms “a” (or “an”), “one or more”, and “at least one” canbe used interchangeably herein unless a limit is specifically stated.

As used herein, the term “enriched” as applied to any stream withdrawnfrom a process means that the withdrawn stream contains a concentrationof a particular component that is higher than the concentration of thatcomponent in the feed stream to the process.

As used herein, the term “expansion device” refers to one or moredevices suitable for reducing the pressure of a fluid in a line (forexample, a liquid stream, a vapor stream, or a multiphase streamcontaining both liquid and vapor). Unless a particular type of expansiondevice is specifically stated, the expansion device may be (1) at leastpartially by isenthalpic means, or (2) may be at least partially byisentropic means, or (3) may be a combination of both isentropic meansand isenthalpic means. Suitable devices for isenthalpic expansion ofnatural gas are known in the art and generally include, but are notlimited to, manually or automatically actuated throttling devices suchas, for example, valves, control valves, Joule-Thomson (J-T) valves, orventuri devices. Suitable devices for isentropic expansion of naturalgas are known in the art and generally include equipment such asexpanders or turbo expanders that extract or derive work from suchexpansion. Suitable devices for isentropic expansion of liquid streamsare known in the art and generally include equipment such as expanders,hydraulic expanders, liquid turbines, or turbo expanders that extract orderive work from such expansion. An example of a combination of bothisentropic means and isenthalpic means may be a Joule-Thomson valve anda turbo expander in parallel, which provides the capability of usingeither alone or using both the J-T valve and the turbo expandersimultaneously. Isenthalpic or isentropic expansion can be conducted inthe all-liquid phase, all-vapor phase, or mixed phases, and can beconducted to facilitate a phase change from a vapor stream or liquidstream to a multiphase stream (a stream having both vapor and liquidphases). In the description of the drawings herein, the reference tomore than one expansion device in any drawing does not necessarily meanthat each expansion device is the same type or size.

As used herein, the term “demethanizer” refers broadly to anydistillation column to separate methane and other volatile componentsfrom ethane and heavier components. The distillation column contains aplurality of vertically spaced trays, one or more packed beds, or somecombination of trays and packing. The trays and/or packing provide thenecessary contact between the liquids falling downward in the column andthe vapors rising upward. The column also includes one or more reboilers(not shown in the drawings) which heat and vaporize a portion of theliquids flowing down the column to provide the stripping vapors whichflow up the column. These vapors strip the methane from the liquids, sothat the bottom liquid product is substantially devoid of methane andcomprised of the majority of the ethane, propane, and heavierhydrocarbons contained in one or more feed streams to the column.

As used herein the term “indirect heat exchange” means the bringing oftwo fluids into heat exchange relation without any physical contact orintermixing of the fluids with each other.

As used herein the terms “turboexpansion” and “turboexpander” meanrespectively method and apparatus for the flow of high pressure fluidthrough a turbine to reduce the pressure and the temperature of thefluid, thereby generating refrigeration and useful work.

As used herein, the term “reboiler” refers to an indirect heat exchangemeans used to at least partially vaporize a stream withdrawn near thebottom of a demethanizer.

As used herein the term “compressor” means a machine that increases thepressure of a gas by the application of work.

As used herein the term “cryogenic pump” means a device for increasingthe head of a fluid stream at cryogenic temperatures.

As used herein, the term “bottoms reboiler” refers to an indirect heatexchange means used to at least partially vaporize a stream withdrawnnear the bottom of a distillation column.

As used herein, the term “bottoms stream” or “bottoms product” refers toan at least partially liquid stream withdrawn from at or near the bottomport of a distillation column.

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or elements recited after the term, where theelement or elements listed after the transition term are not necessarilythe only elements that make up of the subject.

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.” As used herein, the terms “distillation” or “fractionation”refer to the process of physically separating chemical components into avapor phase and a liquid phase based on differences in the components'boiling points at specified temperature and pressure.

As used herein, a “flow regulating device” is any device capable ofregulating flow of liquid from a separator to maintain a desired liquidlevel in the separator, including but not limited to such devices as aliquid regulator, expansion valve, flow regulating pump, or acombination of such devices.

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.” As usedherein, the terms “including,” “includes,” and “include” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.”

As used herein, the term “indirect heat exchange” refers to a processwherein the refrigerant cools the substance to be cooled without actualphysical contact between the refrigerating agent and the substance to becooled. Core-in-kettle heat exchangers and brazed aluminum plate-finheat exchangers are specific examples of equipment that facilitateindirect heat exchange.

As used herein, the terms “natural gas liquids”, “NGL” or “NGLs” referto mixtures of hydrocarbons whose components are, for example, typicallyethane and heavier. Some examples of hydrocarbon components of NGLstreams include ethane, propane, butane, and pentane isomers, benzene,toluene, other aromatic molecules, and possibly small amounts ofmethane, CO₂, and other components.

As used herein, the terms “overhead stream” or “overhead product” refersto an at least partially vapor stream withdrawn from at or near the topport of a fluid separation vessel such as a phase separator,demethanizer or distillation column.

As used herein, the term “reflux” refers to an at least partially liquidstream introduced into the upper portion of a distillation column inorder to increase separation efficiency.

As used herein, the term “side reboiler” refers to an indirect heatexchange means used to heat and at least partially vaporize a streamwithdrawn from between the upper and lower portions of a distillationcolumn.

As used herein, the term “turboexpander” refers to any device forexpanding a stream that is capable of generating useful work.

In general, the invention relates to a process for producing ahelium-enriched vapor stream, a methane-enriched vapor stream, and aliquid stream enriched in hydrocarbons heavier than methane from apressurized, multicomponent, multiphase stream comprising methane (C₁),helium (He), and NGLs, The recovery of helium can be from any stream inthe NGL recovery process that is primarily liquid during the processingby passing the liquid to a phase separator and flashing out ahelium-enriched vapor stream.

FIG. 1 schematically illustrates one embodiment of processing a naturalgas stream to produce a vapor fraction containing substantially all themethane, a liquid fraction containing a large portion of hydrocarbonsheavier than methane, and a helium-enriched fraction. Feed stream 14 isprovided to the system with contaminants, if any, removed from thenatural gas by pretreatment (not shown in the drawings).

Pretreatment is the first consideration in cryogenic processing ofnatural gas. A raw natural gas feed stock suitable for the process ofthis invention may comprise natural gas obtained from a crude oil well(associated gas) or from a gas well (non-associated gas). Thecomposition of the natural gas can vary significantly. Natural gas willtypically contain methane (C₁) as the major component, and willtypically also contain ethane (C₂), propane (C₃), and higherhydrocarbons, diluents such as nitrogen, argon, and helium, andcontaminants such as water, carbon dioxide, mercury, mercaptans,hydrogen sulfide, and iron sulfide. The solubilities of thesecontaminants vary with temperature, pressure, and composition. Atcryogenic temperatures, CO₂, water, and other contaminants can formsolids, which can plug flow passages in cryogenic heat exchangers andother equipment. These potential difficulties can be avoided by removingsuch contaminants. In the following description, it is assumed that thenatural gas stream has been suitably treated to remove unacceptablelevels of mercury, sulfides, carbon dioxide, and other contaminates, anddried to remove water using conventional and well-known processes toproduce a “sweet, dry” natural gas stream. Alternatively, some level ofthese contaminants may be left in the feed gas and become distributedinto the product stream which may require additional treatment at alater stage depending on the intended use of the product.

Referring to FIG. 1, feed stream 14 preferably enters the process at apressure above about 3,100 kPa (450 psia) and more preferably aboveabout 4,800 kPa (700 psia) and a temperature preferably between about−40° C. and −10° C.; however, different pressures and temperatures canbe used, if desired, and the system can be modified accordingly. If feedstream 14 is below about 3,100 kPa (450 psia), the gas stream may bepressurized by any suitable compression means (not shown), which maycomprise one or more compressors. Feed stream 14 should be sufficientlycool such that the feed stream is partly condensed, comprising a mixtureof vapor and liquid. If feed stream 14 is not sufficiently cool,refrigeration may be added to chill the feed gas down by any suitablemeans (not shown).

Feed stream 14 is passed to one or more phase separators 80 whichseparate the multiphase feed stream 14 into vapor stream 16 and a liquidstream 30. The separator 80 has a liquid level control means (not shownin the drawing) which operates in a known manner to control one or moreflow regulating devices 72. Flow regulating device 72 can be any devicecapable of regulating the flow of liquid from the separator 80 tomaintain a desired liquid level in separator 80, such as but not limitedto a liquid regulator, expansion device, or flow regulating pump, or acombination of such equipment. Flow from the flow regulating device 72to demethanizer 88 occurs via stream 31. If the pressure of stream 30 ishigher than the pressure in the demethanizer 88, the flow regulatingdevice 72 can be used to depressurize the liquid to a pressure at ornear the pressure of the demethanizer 88. If the pressure of the stream30 is lower than the pressure in demethanizer 88, a flow regulating pumpmay be used to increase the pressure of stream 30 to a pressure at ornear the pressure of the demethanizer 88.

A first fraction of vapor stream 16 may optionally be withdrawn andpassed as stream 25 to an expansion device 71 wherein the pressure ofthe vapor stream 25 is reduced, thereby effecting a reduction intemperature of this stream 25. Stream 26 exiting the expansion device 71is passed to the demethanizer 88. A second fraction of vapor stream 16is passed as stream 18 to one or more heat exchangers 63 wherein stream18 is cooled by indirect heat exchange against a suitable coolant,preferably overhead vapor from demethanizer 88 (not shown in FIG. 1).This embodiment is not limited to any type of heat exchanger, butbecause of economics, plate-fin, spiral wound, and cold box heatexchangers are preferred. Stream 19 exiting heat exchanger 63 is passedto an expansion device 70 wherein the pressure of stream 19 is reduced,thereby effecting a flashing of liquid and expansion cooling of stream19. Stream 20 exiting the expansion device 70 is passed to one or morephase separators 81, which separate a vapor phase from a liquid phase,which are well known to those of ordinary skill in the art. Vapor stream21 removed from phase separator 81 is enriched in helium. Liquid stream22 exiting the phase separator 81 is passed to an one or more flowregulating devices 73. The separator 81 has a liquid level control means(not shown in the drawing) which operates in a known manner to controlone or more flow regulating devices 73. Flow regulating device 73 can beany device capable of regulating the flow of liquid from the separator81 to maintain a desired liquid level in separator 81, such as but notlimited to a liquid regulator, expansion device, or flow regulatingpump, or a combination of such equipment. Flow from the flow regulatingdevice 73 to demethanizer 88 occurs via stream 23. If the pressure ofstream 22 is higher than the pressure in the demethanizer 88, the flowregulating device 73 can be used to depressurize the liquid to apressure at or near the pressure of the demethanizer 88. If the pressureof the stream 22 is lower than the pressure in demethanizer 88, a flowregulating pump may be used to increase the pressure of stream 22 to apressure at or near the pressure of the demethanizer 88. If the flowregulating device 73 is an expansion device, the pressure of the liquidstream 22 is reduced, thereby effecting some expansion cooling of thisstream. Stream 35 leaves the demethanizer 88 enriched in methane andstream 36 leaves the demethanizer substantially demethanized liquidproduct enriched in NGLs. The demethanizer bottoms stream 36 may bepassed to a conventional fractionation plant (not shown), the generaloperation of which is known to those skilled in the art. Thefractionation plant may comprise one or more fractionation columns whichseparate liquid bottom stream 36 into predetermined amounts of ethane,propane, butane, pentane, and hexane.

FIG. 2 illustrates another embodiment of the disclosure. Feed stream 14,pretreated as described above with respect to FIG. 1, is passed to phaseseparator 80 which comprises one or more separators that separate themultiphase feed stream 14 into a gas phase discharged as vapor stream 16and a liquid stream discharged as liquid stream 30. The liquid stream 30is passed to an flow regulating device 72, preferably an expansiondevice wherein the pressure of the liquid stream 30 is reduced, therebyeffecting a reduction in temperature of stream 30. Stream 31 exiting theexpansion device 72 is passed to phase separator 83 which comprises oneor more separators that separate the multiphase feed stream 31 into avapor phase discharged as vapor stream 32 and a liquid phase dischargedas stream 33. Vapor stream 32 removed from the phase separator 83 isenriched in helium. Liquid stream 33 exiting the phase separator 83 ispassed to an flow regulating device 75. Stream 34 exiting the flowregulating device 75 is passed to the demethanizer 88.

Referring still to FIG. 2, a first fraction of vapor stream 16 is passedas stream 25 to one or more expansion devices 71 wherein the pressure ofstream 25 is reduced resulting in expansion cooling. Stream 26 exitingthe expansion device 71 is passed to an optional phase separator 82which comprises one or more separators that separate the multiphase feedstream 26 into a vapor phase discharged as vapor stream 27 and a liquidstream discharged as stream 28. Vapor stream 27 removed from phaseseparator 82 is enriched in helium. Liquid stream 28 exiting the phaseseparator 82 is passed to one or more flow regulating devices 74. Stream29 exiting the flow regulating device 74 is passed to the demethanizer88. The use of separator 28 and expansion devise 74 to producehelium-enriched stream 27 is optional depending on the economics ofhelium capture.

Referring still to FIG. 2, a second fraction of vapor stream 16 ispassed as stream 18 to one or more heat exchangers 63 wherein stream 18is cooled by indirect heat exchange against a suitable coolant,preferably overhead vapor from the demethanizer 88 (not shown in FIG.2). This embodiment is not limited to any type or number of heatexchangers, but because of economics, plate-fin, spiral wound, and coldbox heat exchangers are preferred. Stream 19 exiting heat exchanger 63is passed to an expansion device 70 wherein the pressure of the liquidstream 19 is reduced, thereby effecting a reduction in temperature ofstream 19. Stream 20 exiting the expansion device 70 is passed to phaseseparator 81, which may comprise one or more phase separators thatseparate a vapor phase from a liquid phase, which are well known tothose of ordinary skill in the art. Vapor stream 21 removed from phaseseparator 81 is enriched in helium. Liquid stream 22 exiting the phaseseparator 81 is passed to one or more flow regulating devices 73. Stream23 exiting the flow regulating device 73 is passed to the demethanizer88. Vapor stream 35 leaves the demethanizer 88 as enriched methane andliquid stream 36 leaves the demethanizer 88 as enriched NGL.

FIG. 3 illustrates another embodiment of the disclosure. The processillustrated in FIG. 3 is similar to the process shown in FIG. 1 exceptthat the vapor stream 35 from the demethanizer 88 is shown as beingfurther processed. Vapor stream 35 is passed to heat exchanger 63 awhich is shown in FIG. 3 as a stand-alone heat exchanger, but preferablyheat exchangers 63 a and 63 are the same heat exchanger in which vaporstream 35 cools by indirect heat exchange vapor stream 18. It should notbe inferred that a heat exchange stage is equivalent to a single heatexchanger. On the contrary, a heat exchange stage should be understoodto include one or more heat exchangers of various kinds which may bedisposed in parallel and/or series configurations. In addition, itshould be understood that other streams (not shown) may be taking partin this heat exchange, such as application of other sources ofrefrigeration. Stream 37 exiting the heat exchanger 63 a is passed toone or more stages of compression, preferably two stages. For the sakeof simplicity, FIG. 3 shows only one compression stage 90. After eachcompression stage, the compressed vapor is preferably cooled byconventional air or water cooler (not shown in FIG. 3). Pressured vaporleaving compression stage 90 is separated into a methane-enrichedproduct stream 38 and recycle vapor stream 39. Vapor stream 39 is cooledby being passed through heat exchanger 63 a and stream 40 exiting theheat exchanger 63 a is passed to phase separator 84 which comprises oneor more separators that separate the stream 40 into a vapor phasedischarged as vapor stream 41 and a liquid stream discharged as stream42. Vapor stream 41 removed from phase separator 84 is enriched inhelium. Liquid stream 42 exiting the phase separator 84 is passed to oneor more flow regulating devices 76. Stream 43 exiting the flowregulating device 76 is passed to the demethanizer 88 as a refluxstream.

FIG. 4 illustrates another embodiment of the disclosure. Referring toFIG. 4, feed gas 110 is passed through cooler 160. A first fraction ofthe cooled stream 111 leaving cooler 160 is passed to cooler 161. Asecond fraction of stream 111 is passed as stream 112 to heat exchanger162 in which stream 112 is cooled by indirect heat exchange against aportion of vapor stream 135 removed from demethanizer 188. The coolers160 and 161 may comprise one or more conventional heat exchangers thatcool the natural gas stream to cryogenic temperatures, preferably downto about −10° C. to −40° C. The coolers 160 and 161 may comprise one ormore heat exchange systems cooled by conventional refrigeration systems,one or more expansion means such as Joule-Thomson valves orturboexpanders, one or more heat exchangers which use liquid from thelower section of the demethanizer 188 as coolant, one or more heatexchangers that use the bottoms product stream 136 of demethanizer 188as coolant, or any other suitable source of cooling. The preferredcooling system will depend on the availability of refrigeration cooling,space limitation, if any, and environmental and safety considerations.Those skilled in the art can select a suitable cooling system takinginto account the operating circumstance of the liquefaction process.Stream 113 exiting heat exchanger 162 and the stream exiting cooler 161are combined as stream 114 which enters phase separator 180 whichproduces vapor stream 116 and a liquid stream 130. The liquid stream 130is passed to a flow regulating device 168, preferably is preferably anexpansion device, more preferably a Joule-Thomson valve, wherein thepressure of the liquid stream 130 is reduced, thereby effecting areduction in temperature of stream 130. Stream 131 exiting the flowregulating device 168 is passed to the demethanizer 188. A firstfraction of vapor stream 116 is passed as stream 125 to an expansiondevice 167, preferably a turboexpander, wherein the pressure of thevapor stream 125 is reduced, thereby effecting a reduction intemperature of this stream. Stream 126 exiting the expansion device 167is passed to the demethanizer 188. A second fraction of vapor stream 116is passed as stream 118 to a heater exchanger 163 wherein stream 118 iscooled by indirect heat exchange by overhead vapor stream 135 fromdemethanizer 188. This embodiment is not limited to any type of heatexchanger 163, but because of economics, plate-fin, spiral wound, andcold box heat exchangers are preferred. Stream 119 exiting heatexchanger 163 is passed to an expansion device 164 wherein the pressureof stream 119 is reduced, thereby effecting a reduction in temperatureof this stream. Stream 120 exiting the expansion device 164 is passed toone or more phase separators 165, which separate a vapor phase from aliquid phase, which are well known to those of ordinary skill in theart. Vapor stream 145 removed from phase separator 165, which isenriched in helium, is passed through heat exchanger 171 and is thenpassed as cooled stream 146 to expansion device 172, preferably a J-Tvalve, wherein the pressure of stream 146 is reduced, thereby effectinga reduction in temperature of stream 146. Stream 147 exiting theexpansion device 172 is passed to phase separator 173 which comprisesone or more separators that separate feed stream 147 into a gas phasedischarged as vapor stream 148 and a liquid stream discharged as stream149. Vapor stream 148 is more enriched in helium than stream 145. Vaporstream 148 is passed through heat exchanger 171 to provide refrigerationduty for vapor stream 145 entering heat exchanger 171. Vapor stream 148exits heat exchanger 171 as crude helium stream 151 which may beupgraded to a higher helium concentration by one or more low temperatureprocessing steps (not shown in the drawings) or other helium enrichmentprocesses (also not shown in the drawings), which are known to thoseskilled in the art to produce helium.

Liquid stream 149 exiting the phase separator 173 is passed to a flowregulating device 174, preferably a J-T valve, wherein the pressure ofthe liquid stream 149 is reduced, thereby effecting a reduction intemperature of this stream. Stream 150 exiting the flow regulatingdevice 174 is passed through heat exchanger 171 to provide additionalrefrigeration duty for vapor stream 145. Stream 152 exiting heatexchanger 171 is passed through heat exchanger 163 to provide coolingfor vapor stream 118. Vapor stream 153 exits heat exchanger 163 as lowpressure (LP) fuel which may supply a portion of the power needed todrive compressors and pumps in the separation process or may be furthercompressed to join stream 144 as methane-enriched product.

Liquid stream 122 exiting phase separator 165 is passed to one or moreflow regulating devices 166, preferably an expansion device wherein thepressure of the liquid stream 122 is reduced, thereby effecting areduction in temperature of this stream. Stream 123 exiting the flowregulating device 166 is passed to the demethanizer 188. Stream 135leaves the demethanizer 188 as enriched methane and stream 136 leavesthe demethanizer substantially demethanized liquid product enriched inNGL. The demethanizer bottoms stream 136 may be passed to a conventionalfractionation plant (not shown), the general operation of which is knownto those skilled in the art. The fractionation plant may comprise one ormore fractionation columns which separate liquid bottom stream 136 intopredetermined amounts of ethane, propane, butane, pentane, and hexane.

Vapor stream 135 removed from the demethanizer 188 providesrefrigeration duty for heat exchanger 163. Warmed stream 135 exits heatexchanger 163 as stream 138, a portion of which is passed as stream 139through heat exchanger 162 to cool part stream 112. Stream 140 exitsheat exchanger 162 and is recombined with stream 138. A part of thevapor stream 138 may be withdrawn from the system as fuel gas (stream141). The remaining portion of vapor stream 138 is compressed by one ormore compressors. Two compressors 169 and 170 are shown in FIG. 4.Optionally, high pressure (HP) fuel (stream 143) may be withdrawn afterany one of the compression stages. Residual gas stream 144 is enrichedin methane.

FIG. 5 illustrates another embodiment of the disclosure. Referring toFIG. 5, pretreated feed gas 210 is passed through cooler 260. A firstfraction of the cooled stream 211 leaving cooler 260 is passed to cooler261. A second fraction of stream 211 is passed as stream 212 to heatexchanger 262 in which stream 212 is cooled by indirect heat exchangeagainst a portion of vapor stream 235 removed from demethanizer 288. Thecoolers 260 and 261 may comprise one or more conventional heatexchangers that cool the natural gas stream to cryogenic temperatures,preferably down to about −10° C. to −40° C. The coolers 260 and 261 maycomprise one or more heat exchange systems cooled by conventionalrefrigeration systems, one or more expansion means such as Joule-Thomsonvalves or turbo expanders, one or more heat exchangers which use liquidfrom the lower section of the demethanizer 288 as coolant, one or moreheat exchangers that use the bottoms product stream 236 of demethanizer288 as coolant, or any other suitable source of cooling. The preferredcooling system will depend on the availability of refrigeration cooling,space limitation, if any, and environmental and safety considerations.Those skilled in the art can select a suitable cooling system takinginto account the operating circumstance of the liquefaction process.Stream 213 exiting heat exchanger 262 and the stream exiting cooler 261are combined as stream 214 which enters phase separator 280 whichproduces vapor stream 216 and a liquid stream 230. The liquid stream 230is passed to a flow regulating device 268, preferably a Joule-Thomsonvalve, wherein the pressure of the liquid stream 230 is reduced, therebyeffecting a reduction in temperature of this stream. Stream 231 exitingthe flow regulating device 268 is passed to the demethanizer 288. Afirst fraction of vapor stream 216 is passed as stream 225 to anexpansion device 267, preferably a turboexpander, wherein the pressureof the vapor stream 225 is reduced, thereby effecting a reduction intemperature of this stream. Stream 226 exiting the expansion device 267is passed to the demethanizer 288. A second fraction of vapor stream 216is passed as stream 218 to a heat exchanger 263 wherein stream 218 iscooled by indirect heat exchange by overhead vapor stream 235 fromdemethanizer 288. This embodiment is not limited to any type of heatexchanger 263, but because of economics, plate-fin, spiral wound, andcold box heat exchangers are preferred. Stream 219 exiting heatexchanger 263 is passed to an expansion device 264, preferably a J-Tvalve, wherein the pressure of stream 219 is reduced, thereby effectinga reduction in temperature of this stream. Stream 220 exiting theexpansion device 264 is passed to one or more phase separators 265,which separate a vapor phase from a liquid phase, which are well knownto those of ordinary skill in the art. Vapor stream 221 removed fromphase separator 265, which is enriched in helium, is combined with vaporstream 283, and the combined stream 223 is passed to heat exchanger 271.Cooled stream 246 exits heat exchanger 271 and is passed to an expansiondevice 272 wherein the pressure of stream 246 is reduced, therebyeffecting a reduction in temperature of stream 246. Stream 247 exitingthe expansion device 272 is passed to phase separator 273 whichcomprises one or more separators that separate feed stream 247 into agas phase discharged as vapor stream 248 and a liquid stream dischargedas liquid stream 249. Vapor stream 248 removed from phase separator 273is more enriched in helium than stream 221. Vapor stream 248 is passedthrough heat exchanger 271 to provide refrigeration duty for vaporstream 223. Stream 248 exits heat exchanger 271 as crude helium stream251, which may be upgraded to a higher helium concentration by one ormore processing steps (not shown) to produce helium.

Liquid stream 249 exiting the phase separator 273 is passed to flowregulating device 274, preferably a Joule-Thomson valve, wherein thepressure of the liquid stream 249 is reduced, thereby effecting areduction in temperature of this stream. Stream 250 exiting theexpansion device 274 is passed through heat exchanger 271 to providerefrigeration assistance for stream 223 entering heat exchanger 271.Stream 252 exiting heat exchanger 271 is passed through heat exchanger263 to provide refrigeration duty for cooling vapor stream 218. Vaporstream 253 exits heat exchanger 263 as a gas which, for example, can beused as low pressure (LP) fuel, which may supply a portion of the powerneeded to drive compressors and pumps in the separation process.

Vapor stream 235 removed from the demethanizer 288 providesrefrigeration duty for heat exchanger 263. Warmed stream 235 exits heatexchanger 263 as stream 238, a first portion of which is passed asstream 239 through heat exchanger 262 to cool part of the feed stream212. Stream 240 exits heat exchanger 262 and is recombined with stream238. A second portion of stream 238 is passed through heat exchanger 276and recombined with stream 240. A portion of the vapor stream 238 may bewithdrawn from the system as fuel gas (stream 241). The remainingportion of vapor stream 238 is compressed by one or more compressors.Two compressors 269 and 270 are shown in FIG. 5. Optionally, highpressure (HP) fuel (stream 243), enriched in methane, may be withdrawnafter any one of the compression stages 269 and 270. Optionally,enriched methane in stream 243 may also be drawn as a product stream.One portion of stream 244 exits the process as residual gas enriched inmethane and a second portion of stream 244 is passed as stream 275 toheat exchanger 276. Stream 277 exiting heat exchanger 276 is passedthrough heat exchanger 263 for further cooling. Stream 278 exiting heatexchanger 263 is passed to expansion device 279, preferably aJoule-Thomson valve, wherein the pressure of the stream 278 is reduced,thereby effecting a reduction in temperature of this stream. Stream 281exiting the expansion device 279 is passed to phase separator 282 whichproduces vapor stream 283 and a liquid stream 284. Vapor stream 283 ismerged with vapor stream 221. Liquid stream 284 is passed to flowregulating device 285, preferably a pressure reduction means, and morepreferably a Joule-Thomson valve, wherein the pressure of the stream 284is reduced, thereby effecting a reduction in temperature of this stream.Stream 286 exiting the flow regulating device 285 is passed todemethanizer 288.

Liquid stream 222 from phase separator 265 is passed to flow regulatingdevice 266, preferably a pressure reduction means, and more preferably aJoule-Thomson valve, wherein the pressure of the stream 222 is reduced,thereby effecting a reduction in temperature of this stream. Stream 224exiting the flow regulating device 266 is passed to demethanizer 288.

Liquid stream 236 leaves the demethanizer 288 as substantiallydemethanized liquid product enriched in NGL. The demethanizer bottomsstream 236 may be passed to a conventional fractionation plant (notshown), the general operation of which is known to those skilled in theart. The fractionation plant may comprise one or more fractionationcolumns which separate liquid bottom stream 236 into predeterminedamounts of ethane, propane, butane, pentane, and hexane.

FIG. 6 illustrates still another embodiment of the disclosure which issimilar to the process illustrated in FIG. 5 except that recycle vaporstream 278 is passed to phase separator 265 instead of being passed tophase separator 282 as shown in FIG. 5. In FIG. 6, the phase separator282 shown in FIG. 5 is omitted.

FIG. 7 illustrates another embodiment of the disclosure which is similarto the embodiment shown in FIG. 1 except that refrigeration systems areused to cool vapor streams in place of expansion devices as shown inFIG. 1. Feed stream 300, pretreated as described above with respect toFIG. 1, is passed to phase separator 301 which comprises one or moreseparators that separate the multiphase feed stream 300 into a gas phasedischarged as vapor stream 302 and a liquid stream discharged as liquidstream 303. The liquid stream 303 is passed to an flow regulating device304, preferably an expansion device wherein the pressure of the liquidstream 303 is reduced, thereby effecting a reduction in temperature ofstream 303. Stream 305 exiting the flow regulating device 304 is passedto the demethanizer 388.

Referring still to FIG. 7, vapor stream 302 is passed to one or moreheat exchangers 306 wherein stream 302 is cooled by indirect heatexchange against a suitable coolant, preferably overhead vapor (notshown in FIG. 7) from demethanizer 388. Stream 307 exiting the heatexchanger 306 is passed to phase separator 308 which comprises one ormore separators that separate the multiphase stream 307 into a vaporphase discharged as vapor stream 309 and a liquid stream discharged asstream 310. Vapor stream 309 is passed to one or more heat exchangers311 wherein stream 309 is cooled by indirect heat exchange. Stream 312exiting heat exchanger 311 is passed to phase separator 313 whichcomprises one or more separators that separate the multiphase stream 312into a vapor stream 314 which is enriched in helium and a liquid bottomsstream 315. Liquid stream 315 exiting the phase separator 313 is passedto one or more flow regulating devices 316. Stream 317 exiting the flowregulating device 316 is passed to the demethanizer 388. Liquid stream310 from phase separator 308 is passed to a flow regulating device 320.Stream 321 exiting the flow regulating device 320 is passed to thedemethanizer 388. Vapor stream 318 leaves the demethanizer 388 asenriched methane and liquid stream 319 leaves the demethanizer 388 asenriched NGL.

The embodiments disclosed herein can be used for new plant designs orcan be used to retrofit existing NGL recovery plants to recover helium.For example, any of the embodiments of FIGS. 1, 2 and 4 may be installedas a retrofit to a pre-existing Gas Subcooled Process (“GSP”) of thetype disclosed in U.S. Pat. Nos. 4,140,504; 4,157,904; and 4,278,457 andthe embodiments of FIGS. 3, 5, and 6 may be installed as a retrofit to apre-existing Recycle Split-vapor Process (“RSV”) of the type disclosedin U.S. Pat. No. 5,568,737. The additional equipment added to anexisting NGL plant would not significantly affect the recovery of NGLfrom the natural gas. The amount of helium recovered, as well as thepurity of the helium-enriched product streams (stream 21 in FIG. 1;streams 21, 27, and 32 in FIG. 2; streams 41 and 21 in FIG. 3; andstreams 151 in FIGS. 4, 5, and 6) can be regulated by persons skilled inthe art to meet desired product compositions and flow rates by adjustingthe pressure drop through the various expansion devices. Moreover, theretrofitted helium recovery unit disclosed herein can flexibly adapt tovariations in the rate and composition of the natural gas feed stream,and can readily be adjusted to change the composition of thehelium-enriched product streams.

One benefit of using the invention over methods used in the past is theability to integrate helium recovery with existing units or processes ina natural gas plant. Helium recovery schemes in the past typically haveseparate unit operations from NGL recovery units or processes.Integration of helium recovery and NGL recovery minimizes the capitalcost associated with the entire facility, which afford more heliumrecovery in gas plants.

EXAMPLES

A simulated mass and energy balance was carried out to illustrate theembodiments illustrated in the FIGS. 4 and 5, and the results are setforth in Tables 1 and 2 below. The data presented in the Tables beloware offered to provide a better understanding of the embodiments shownin FIGS. 4 and 5, but the invention is not to be construed asunnecessarily limited thereto. The temperatures, pressures, and flowrates presented in the Tables are not to be considered as limitationsupon the invention which can have many variations in operatingconditions in view of the teachings herein. The Table 1 corresponds tothe process illustrated in FIG. 4 and Table 2 corresponds to the processillustrated in FIG. 5.

The data were obtained using a commercially available process simulationprogram called HYSYS™, version 2004.1 (13.2.0.6510), available fromHyprotech Ltd.; however, other commercially available process simulationprograms can be used to develop similar data, including for exampleHYSIM™, PROII™, and ASPEN PLUS™, all of which are familiar to those ofordinary skill in the art.

TABLE 1 C₁ C₂ C₃ He N₂ Stream Vapor Temp. Pressure Molar Flow (mole(mole (mole (mole (mole Number Fraction ° C. kPa (kg mole/h) fraction)fraction) fraction) fraction) fraction) 110 1.0 26.17 6696 4.052e+0040.8665 0.0560 0.0201 0.0005 0.0400 111 1.0 14.79 6627 4.052e+004 0.86650.0560 0.0201 0.0005 0.0400 112 1.0 14.79 6627 2.634e+004 0.8665 0.05600.0201 0.0005 0.0400 113 0.9622 −33.26 6558 2.634e+004 0.8665 0.05600.0201 0.0005 0.0400 114 0.9753 −26.00 6558 4.052e+004 0.8665 0.05600.0201 0.0005 0.0400 116 1.0 −25.91 6558 3.952e+004 0.8771 0.0541 0.01790.0005 0.0408 118 1.0 −25.91 6558 1.027e+004 0.8771 0.0541 0.0179 0.00050.0408 119 0.0 −97.0 6489 1.027e+004 0.8771 0.0541 0.0179 0.0005 0.0408120 0.1330 −107.0 2138 1.027e+004 0.8771 0.0541 0.0179 0.0005 0.0408 1220.0 −107.0 2138 8908 0.8792 0.0619 0.0207 0.0001 0.0273 123 0.0001−107.0 2137 8908 0.8792 0.0619 0.0207 0.0001 0.0273 126 0.9377 −75.02144 2.924e+004 0.8771 0.0541 0.0179 0.0005 0.0408 131 0.3367 −44.222151 1037 0.4337 0.1262 0.1273 0.0 0.0070 135 1.0 −99.75 2089 3.580e+0040.9467 0.0122 0.0002 0.0005 0.0403 136 0.0 18.42 2124 3384 0.0100 0.54030.2458 0.0 0.0 138 1.0 −51.80 1986 3.580e+004 0.9467 0.0122 0.00020.0005 0.0403 139 1.0 −51.80 1986 3.222e+004 0.9467 0.0122 0.0002 0.00050.0403 140 1.0 10.68 1917 3.222e+004 0.9467 0.0122 0.0002 0.0005 0.0403142 1.0 34.35 2668 3.513e+004 0.9467 0.0122 0.0002 0.0005 0.0403 144 1.099.12 5400 6.786e+004 0.9467 0.0122 0.0002 0.0005 0.0403 145 1.0 −107.02138 1367 0.8635 0.0034 0.0001 0.0037 0.1292 146 0.0025 −171.9 2133 13670.8635 0.0034 0.0001 0.0037 0.1292 147 0.0063 −171.5 500.0 1367 0.86350.0034 0.0001 0.0037 0.1292 148 1.0 −171.5 500.0 8.650 0.0805 0.0 0.00.5490 0.3704 149 0.0 −171.5 500.0 1358 0.8684 0.0035 0.0001 0.00020.1277 150 0.0114 −172.4 200.0 1358 0.8684 0.0035 0.0001 0.0002 0.1277151 1.0 −136.1 495.0 8.650 0.0805 0.0 0.0 0.5490 0.3704 153 1.0 −51.80175.0 1358 0.8684 0.0035 0.0001 0.0002 0.1277

TABLE 2 C₁ C₂ C₃ He N₂ Stream Vapor Temp. Pressure Molar Flow (mole(mole (mole (mole (mole Number Fraction ° C. kPa (kg mole/h) fraction)fraction) fraction) fraction) fraction) 210 1.0 26.17 6696 4.052e+0040.8665 0.0560 0.0201 0.0005 0.0400 211 0.9997 12.38 6627 4.052e+0040.8665 0.0560 0.0201 0.0005 0.0400 212 0.9997 12.38 6627 2.634e+0040.8665 0.0560 0.0201 0.0005 0.0400 213 0.9784 −23.75 6558 2.634e+0040.8665 0.0560 0.0201 0.0005 0.0400 214 0.9753 −26.00 6558 4.052e+0040.8665 0.0560 0.0201 0.0005 0.0400 216 1.0 −25.91 6558 3.952e+004 0.87710.0541 0.0179 0.0005 0.0408 218 1.0 −25.91 6558 1.304e+004 0.8771 0.05410.0179 0.0005 0.0408 219 0.0 −104.3 6489 1.304e+004 0.8771 0.0541 0.01790.0005 0.0408 220 0.0517 −108.5 2138 1.304e+004 0.8771 0.0541 0.01790.0005 0.0408 221 1.0 −108.5 2138 674.5 0.8302 0.0030 0.0001 0.00810.1586 222 0.0 −108.5 2138 1.237e+004 0.8796 0.0569 0.0189 0.0001 0.0344223 1.0 −108.9 2138 826.4 0.8367 0.0024 0.0001 0.0075 0.1532 226 0.9377−75.00 2144 2.648e+004 0.8771 0.0541 0.0179 0.0005 0.0408 231 0.3367−44.22 2151 1037 0.4337 0.1262 0.1273 0.0 0.0070 235 1.0 −106.8 20893.811e+004 0.9562 0.0018 0.0 0.0004 0.0415 236 0.0 16.70 2124 37560.0059 0.5864 0.2237 0.0 0.0 238 1.0 −33.19 1986 3.811e+004 0.95620.0018 0.0 0.0004 0.0415 239 1.0 −33.19 1986 3.533e+004 0.9562 0.00180.0 0.0004 0.0415 240 1.0 8.327 1917 3.533e+004 0.9562 0.0018 0.0 0.00040.0415 244 1.0 107.2 5400 6.820e+004 0.9562 0.0018 0.0 0.0004 0.0415 2460.0068 −171.8 2133 826.4 0.8367 0.0024 0.0001 0.0075 0.1532 247 0.0145−171.6 500.0 826.4 0.8367 0.0024 0.0001 0.0075 0.1532 248 1.0 −171.6500.0 11.95 0.0783 0.0 0.0 0.5032 0.4185 249 0.0 −171.6 500.0 814.40.8479 0.0025 0.0001 0.0002 0.1493 250 0.0211 −173.5 200.0 814.4 0.84790.0025 0.0001 0.0002 0.1493 251 1.0 −137.7 495.0 11.95 0.0783 0.0 0.00.5032 0.4185 253 1.0 −33.19 175.0 814.4 0.8479 0.0025 0.0001 0.00020.1493 275 1.0 58.00 5330 2133 0.9562 0.0018 0.0 0.0004 0.0415 277 1.0−32.00 5261 2133 0.9562 0.0018 0.0 0.0004 0.0415 278 0.0 −104.3 51922133 0.9562 0.0018 0.0 0.0004 0.0415 281 0.0712 −110.2 2138 2133 0.95620.0018 0.0 0.0004 0.0415 283 1.0 −110.2 2138 151.9 0.8658 0.0001 0.00.0046 0.1295 284 0.0 −110.2 2138 1981 0.9631 0.0020 0.0 0.0001 0.0348

It should be understood that the preceding is merely a detaileddescription of specific embodiments of this invention and that numerouschanges, modifications, and alternatives to the disclosed embodimentscan be made in accordance with the disclosure here without departingfrom the scope of the invention. The preceding description, therefore,is not meant to limit the scope of the invention. Rather, the scope ofthe invention is to be determined only by the appended claims and theirequivalents.

1. A process for producing a helium-enriched vapor stream, amethane-enriched vapor stream, and a liquid stream enriched inhydrocarbons heavier than methane from a pressurized, multicomponent,multiphase stream comprising methane (C₁), helium (He) and hydrocarbonsheavier than methane (C₂₊), the process comprising the steps of: (a)cooling the multiphase stream to produce at least one vapor streamenriched in helium and at least one liquid stream; (b) withdrawing atleast a portion of the at least one vapor stream as a helium-enrichedproduct stream; (c) passing at least a portion of the at least oneliquid stream to a demethanizer; (d) withdrawing from the demethanizer avapor enriched in methane (C₁); and (e) withdrawing from thedemethanizer a liquid enriched in hydrocarbons heavier than methane(C₂₊).
 2. The process of claim 1 wherein the step of cooling the feedstream is carried out using one or more heat exchangers.
 3. The processof claim 1 further comprising, after cooling the multiphase stream,passing the cooled multiphase stream to a phase separator whichseparates the cooled feed stream into the at least one vapor stream andthe at least one liquid stream.
 4. The method of claim 3 furthercomprising withdrawing the at least one liquid stream from the phaseseparator and passing the at least one liquid stream to a flowregulating device and thereafter passing at least a portion of the atleast one liquid stream to the demethanizer.
 5. A process for producinga helium-enriched vapor stream, a methane-enriched vapor stream, and aliquid stream enriched in hydrocarbons heavier than methane (C₂₊) from apressurized, multicomponent, multiphase feed stream comprising methane(C₁), helium (He) and hydrocarbons heavier than methane (C₂₊), theprocess comprising the steps of: (a) passing the feed stream into afirst phase separator to produce a first vapor phase and a first liquidphase; (b) withdrawing the first vapor phase from the first phaseseparator; (c) separating the first vapor phase into a second vaporphase and a third vapor phase; (d) cooling the second vapor phase byindirect heat exchange in a heat exchanger; (e) expanding the cooledsecond vapor phase to produce a reduced-pressure vapor phase andreduced-pressure liquid phase, and passing the reduced-pressure vaporand liquid phases to a second phase separator; (f) withdrawing from thesecond phase separator a helium-enriched vapor phase; (g) withdrawingliquid from the second phase separator and passing the withdrawn liquidto a first flow regulating device; (h) passing the liquid from the flowregulating device to a demethanizer; (i) expanding the third vapor phaseof step (c) to produce a reduced-pressure vapor phase andreduced-pressure pressure liquid phase, and passing the reduced-pressurevapor and liquid phases to the demethanizer; (j) withdrawing liquid fromthe first phase separator and passing the withdrawn liquid to a secondflow regulating device; (k) passing the liquid from the second flowregulating device to the demethanizer; (l) withdrawing from thedemethanizer a vapor enriched in methane (C₁); and (m) withdrawing fromthe demethanizer a liquid enriched in hydrocarbons heavier than methane(C₂₊).
 6. The process of claim 5 wherein the first flow regulatingdevice is an expansion device.
 7. The process of claim 6 wherein theexpansion device is a J-T valve.
 8. The process of claim 6 wherein theexpansion device is a turboexpander.
 9. The process of claim 5 whereinat least one of the first flow regulating device or the second flowregulating devices is a flow regulating pump.
 10. The process of claim 5wherein the second flow regulating device is an expansion device. 11.The process of claim 10 wherein the expansion device is a J-T valve. 12.The process of claim 10 wherein the expansion device is a turboexpander.13. The process of claim 10 wherein the second flow regulating device isliquid regulator.
 14. A process for separating a feed stream comprisingmethane (C₁), and hydrocarbons heavier than methane, and helium into agas fraction containing substantially all the methane, a liquid fractioncontaining a large portion of the hydrocarbons heavier than methane, anda helium-enriched fraction, the process comprising the steps of: (a)providing the feed stream at a temperature sufficiently low for feedstream to be multiphase; (b) passing the multiphase feed stream of step(a) to a phase separator produce a first vapor stream and a first liquidstream; (c) passing the first liquid stream to a first flow regulatingdevice; (d) passing the liquid from the first flow regulating device toa demethanizer; (e) passing a first fraction of the first vapor streamto an expander device to lower the pressure of the first fraction,thereby cooling the first fraction of the vapor stream to produce asecond multiphase stream; (f) passing the second multiphase stream tothe demethanizer; (g) passing a second fraction of the first vaporstream to a heat exchanger to cool the second fraction of the firstvapor stream to a lower temperature, thereby producing a cooled streamand passing the cooled stream to an expander device thereby producing athird multiphase stream; (h) passing the third multiphase stream of step(g) to a separator to produce a helium-enriched vapor stream and asecond liquid stream; (i) passing the second liquid to a second flowregulating device; (j) passing the second liquid from the second flowregulating device to the demethanizer; (k) withdrawing a vapor streamfrom the demethanizer enriched in methane; and (l) withdrawing a liquidstream from the demethanizer enriched in hydrocarbons heavier thanmethane.
 15. The process of claim 14 wherein the first flow regulatingdevice is an expansion device.
 16. The process of claim 15 wherein theexpansion device is a J-T valve.
 17. The process of claim 15 wherein theexpansion device is a turboexpander.
 18. The process of claim 14 whereinthe first flow regulating device is a cryogenic pump.
 19. The process ofclaim 14 wherein the second flow regulating device is an expansiondevice.
 20. The process of claim 19 wherein the expansion device is aJ-T valve.
 21. The process of claim 19 wherein the expansion device is aturboexpander.
 22. The process of claim 14 wherein the second flowregulating device is a cryogenic pump.
 23. A process for separating afeed stream comprising methane, hydrocarbons heavier than methane, andhelium into a gas fraction rich in methane, a liquid fraction rich inhydrocarbons heavier than methane, and vapor fraction rich in helium,the process comprising the steps of: (a) providing the feed stream at atemperature sufficiently low for the feed stream to be multiphase; (b)passing the multiphase stream of step (a) to a first separator produce afirst vapor stream and a first liquid stream; (c) passing the firstliquid stream to a first flow regulating device; (d) passing the liquidstream from the first flow regulating device to a second separator toproduce a first helium-enriched vapor stream and a second liquid stream;(e) passing the second liquid stream to a second flow regulating device;(f) passing the second liquid stream from the second flow regulatingdevice to a demethanizer; (g) passing a first fraction of the firstvapor stream to an expansion device, thereby cooling the first fractionto produce a cooled stream; (h) passing the cooled stream of step (g) toa third separator to produce a vapor stream and a third liquid stream;(i) passing the third liquid stream to a third flow regulating device;(j) passing the third liquid stream from the third flow regulatingdevice to the demethanizer; (k) passing a second fraction of the firstvapor stream to a heat exchanger to cool the second fraction a lowertemperature, and thereafter passing the cooled second fraction to anexpander device to further cool the second fraction; (l) passing thecooled second fraction from the expander device of step (k) to a fourthseparator to produce a helium-enriched vapor stream and a fourth liquidstream; (m) passing the fourth liquid stream to a fourth flow regulatingdevice; (n) passing fourth liquid stream to the demethanizer; (o)withdrawing a vapor stream from the demethanizer enriched in methane;(p) withdrawing a liquid stream from the demethanizer enriched inhydrocarbons heavier than methane.
 24. The process of claim 23 whereinat least one of the first, second, third and fourth flow regulatingdevices is an expansion device.
 25. The process of claim 24 wherein theexpansion device is selected from a J-T valve or turboexpander.
 26. Theprocess of claim 23 wherein at least one of the first, second, third,and fourth flow regulating devices is a cryogenic pump.
 27. A processfor separation of hydrocarbons to separate a feed stream containing atleast methane, a hydrocarbon less volatile than methane, and helium,into a residue gas enriched with methane and lean in the hydrocarbonless volatile than methane, a heavier fraction lean in methane andenriched with the hydrocarbon less volatile than methane, and a fractionenriched in helium, the process comprising the steps of: (a) providing afeed stream that is partly condensed; (b) separating the feed streaminto a vapor and a first liquid; (c) passing the liquid separated instep (b) to a first flow regulating device; (d) passing the liquid fromthe flow regulating device to a distillation column; (e) dividing thevapor obtained in step (b) into a first portion and a second portion;(f) expanding a first portion of the vapor separated in step (b),thereby producing a second reduced pressure stream, and passing thesecond reduced pressure stream to the distillation column; (g) coolingthe second portion of the vapor separated in step (b) in a heatexchanger and expanding the cooled second vapor portion, thereby partlycondensing the cooled second vapor portion; (h) separating partlycondensed, cooled second vapor portion of step (g) into ahelium-enriched stream and a second liquid; (i) passing the secondliquid separated in step (h) to a second flow regulating device; (j)passing second liquid from the second flow regulating device to thedistillation column; and (k) recovering from the distillation column avapor stream enriched in methane and a liquid enriched in hydrocarbonsless volatile than methane.
 28. A process for separating a natural gasstream comprising methane, hydrocarbons heavier than methane, and heliuminto a gas fraction rich in methane, a liquid fraction rich inhydrocarbons heavier than methane, and vapor fraction rich in helium,the process comprising the steps of: (a) providing the natural gasstream at a temperature sufficiently low for the natural gas stream tobe multiphase; (b) passing the natural gas stream of step (a) to a firstphase separator to produce a first vapor stream and a first liquidstream; (c) passing the first liquid stream to a first flow regulatingdevice; (d) passing the liquid stream from the first flow regulatingdevice to a demethanizer; (e) passing the first vapor stream to an afirst heat exchanger, thereby cooling the first vapor fraction toproduce second multiphase stream; (f) passing the second multiphasestream of step (e) to a second phase separator to produce a second vaporstream and second liquid stream; (g) passing the second liquid stream toa second flow regulating device; (h) passing the second liquid from thesecond flow regulating device to the demethanizer; (i) passing thesecond vapor stream to a second heat exchanger, thereby cooling thesecond vapor fraction to produce third multiphase stream; (j) passingthe third multiphase stream of step (i) to a third phase separator toproduce a third vapor stream that is enriched in helium and a thirdliquid stream; (k) passing the third liquid stream to a third flowregulating device; (l) passing the third liquid from the third flowregulating device to the demethanizer; (m) withdrawing a vapor streamfrom the demethanizer enriched in methane; and (n) withdrawing a liquidstream from the demethanizer enriched in hydrocarbons heavier thanmethane.